Automated Dielectrophoretic Tweezers-Based Force Spectroscopy System in a Microfluidic Device.

We reported an automated dielectrophoretic (DEP) tweezers-based force spectroscopy system to examine intermolecular weak binding interactions, which consists of three components: (1) interdigitated electrodes and micro-sized polystyrene particles used as DEP tweezers and probes inside a microfluidic device, along with an arbitrary function generator connected to a high voltage amplifier; (2) microscopy hooked up to a high-speed charge coupled device (CCD) camera with an image acquisition device; and (3) a computer aid control system based on the LabVIEW program. Using this automated system, we verified the measurement reliability by measuring intermolecular weak binding interactions, such as hydrogen bonds and Van der Waals interactions. In addition, we also observed the linearity of the force loading rates, which is applied to the probes by the DEP tweezers, by varying the number of voltage increment steps and thus affecting the linearity of the force loading rates. This system provides a simple and low-cost platform to investigate intermolecular weak binding interactions.

Detection of Silver Ions Using Dielectrophoretic Tweezers-Based Force Spectroscopy.

Understanding of the interactions of silver ions (Ag+) with polynucleotides is important not only to detect Ag+ over a wide range of concentrations in a simple, robust, and high-throughput manner but also to investigate the intermolecular interactions of hydrogen and coordinate interactions that are generated due to the interplay of Ag+, hydrogen ions (H+), and polynucleotides since it is critical to prevent adverse environmental effects that may cause DNA damage and develop strategies to treat this damage. Here, we demonstrate a novel approach to simultaneously detect Ag+ satisfying the above requirements and examine the combined intermolecular interactions of Ag+-polycytosine and H+-polycytosine DNA complexes using dielectrophoretic tweezers-based force spectroscopy. For this investigation, we detected Ag+ over a range of concentrations (1 nM to 100 µM) by quantifying the rupture force of the combined interactions and examined the interplay between the three factors (Ag+, H+, and polycytosine) using the same assay for the detection of Ag+. Our study provides a new avenue not only for the detection of heavy metal ions but also for the investigation of heavy metal ions-polynucleotide DNA complexes using the same assay.

Characterization of the Stiffness of Multiple Particles Trapped by Dielectrophoretic Tweezers in a Microfluidic Device.

Characterization of the stiffness of multiple particles trapped by tweezers-based force spectroscopy is a key step in building simple, high-throughput, and robust systems that can investigate the molecular interactions in a biological process, but the technology to characterize it in a given environment simultaneously is still lacking. We first characterized the stiffness of multiple particles trapped by dielectrophoretic (DEP) tweezers inside a microfluidic device. In this characterization, we developed a method to measure the thermal fluctuations of the trapped multiple particles with DEP tweezers by varying the heights of the particles in the given environment at the same time. Using the data measured in this controlled environment, we extracted the stiffness of the trapped particles and calculated their force. This study not only provides a simple and high-throughput method to measure the trap stiffness of multiple particles inside a microfluidic device using DEP tweezers but also inspires the application of the trapped multiple particles to investigate the dynamics in molecular interactions.

Real-Time Analysis of Cellular Response to Small-Molecule Drugs within a Microfluidic Dielectrophoresis Device.

Quantitative detection of the biological properties of living cells is essential for a wide range of purposes, from the understanding of cellular characteristics to the development of novel drugs in nanomedicine. Here, we demonstrate that analysis of cell biological properties within a microfluidic dielectrophoresis device enables quantitative detection of cellular biological properties and simultaneously allows large-scale measurement in a noise-robust and probeless manner. Applying this technique, the static and dynamic biological responses of live B16F10 melanoma cells to the small-molecule drugs such as N-ethylmaleimide (NEM) and [(dihydronindenyl)oxy]alkanoic acid (DIOA) were quantitatively and statistically examined by investigating changes in movement of the cells. Measurement was achieved using subtle variations in dielectrophoresis (DEP) properties of the cells, which were attributed to activation or deactivation of K(+)/Cl(-) cotransporter channels on the cell membrane by the small-molecule drugs, in a microfluidic device. On the basis of quantitative analysis data, we also provide the first report of the shift of the complex permittivity of a cell induced by the small-molecule drugs. In addition, we demonstrate interesting quantifiable parameters including the drug effectiveness coefficient, antagonistic interaction coefficient, kinetic rate, and full width at half-maximum, which corresponded to changes in biological properties of B16F10 cells over time when NEM and DIOA were introduced alone or in combination. Those demonstrated parameters represent very useful tools for evaluating the effect of small-molecule drugs on the biological properties of cells.

Vascular disease prevalence and risk factors in a screened Korean male population.

BACKGROUND: Vascular diseases, such as carotid artery stenosis (CAS), abdominal aortic aneurysm (AAA), and peripheral arterial occlusive disease (PAD) of the lower limb, are common in elderly men. These diseases have not been thoroughly reported in Eastern countries as well as in Western countries. We compare the prevalence rates in Korea with previous reports, and evaluate correlations between known risk factors and these conditions in this population. MATERIALS AND METHODS: From November 2008 to December 2012, elderly men (≥65 years) were randomly referred from the Incheon Federation of the Korean Senior Citizens' Association, which is one of the major organizations representing retired individuals in Korea. CAS was defined as ≥50% of internal CAS, AAA was defined as ≥3 cm aortic diameter, and PAD of the lower limb was defined as an ankle brachial index ≤0.9. RESULTS: The average age was 72.14 ± 5.15 years. CAS was detected in 116 subjects (7.2%), AAA was detected in 52 subjects (3.2%), and PAD was detected in 79 subjects (4.9%). On multivariate analysis, octogenarian status and coronary artery disease were significantly associated with CAS and current smoking was significantly associated with PAD (P < 0.001). CONCLUSIONS: The Korean prevalence rates of CAS and PAD in this study are similar to previous reports. The prevalence of AAA in Korea is lower compared with western reports, but higher than previous Asian reports. It is presently necessary to conduct major clinical studies throughout Asian countries to prepare for a rapid increase in the prevalence of major vascular diseases in Asia.

Prognostic Value of Preoperative Serum Levels of Five Tumor Markers (Carcinoembryonic Antigen, CA19-9, Alpha-fetoprotein, CA72-4, and CA125) in Gastric Cancer.

BACKGROUND/AIMS: There is no known specific tumor marker for gastric cancer, although several tumor markers have been used. The aim of this study was to investigate the prognostic significance of preoperative carcinoembryonic antigen (CEA), CA 19-9, alpha-fetoprotein (AFP), CA 72-4, and CA 125 levels in patients with gastric cancer. METHODOLOGY: Medical records of 1,253 patients who were diagnosed with gastric adenocarcinoma were retrospectively reviewed. The clinicopathologic characteristics and disease-free survival rate of the patients were compared between positive and negative CEA, CA 19-9, AFP, CA 72-4, and CA 125 groups of patients. Additionally, the prognostic significance of each tumor marker was assessed by multivariate analysis. RESULTS: CEA, CA19-9, and CA72-4 were more frequently positive in patients with lymphatic and venous invasion, serosal involvement, and lymph node metastasis. The 5-year overall survival and disease free survival rates were significantly associated with elevated serum levels of CEA, CA 19-9, and CA 72-4. The depth of invasion and CA 19-9 were independent prognostic factors. Patients with elevated serum levels of CA 19-9 showed a 3.35-fold higher risk of death than patients with low levels of the marker. CONCLUSIONS: CA 19-9 has prognostic significance in gastric cancer, and a high preoperative serum level of CA 19-9 can be useful for estimating worse prognosis and a higher recurrence of gastric cancer.

Recycled, Contaminated, Crumpled Aluminum Foil-Driven Triboelectric Nanogenerator.

With rapid urbanization and global population growth, the amount of wasted aluminum foil is significantly increasing. Most deformed and contaminated foil is difficult to recycle; hence, it is landfilled or incinerated, causing environmental pollution. Therefore, using aluminum foil waste for electricity may be conducive to addressing environmental problems. In this regard, various literatures have explored the concept of energy generation using foil, while a crumple ball design for this purpose has not been studied. Thus, a recycled foil-based crumpled ball triboelectric nanogenerator (RFCB-TENG) is proposed. The crumpled ball design can minimize the effects of contamination on foil, ensuring efficient power output. Moreover, owing to novel crumpled design, the RFCB-TENG has some outstanding characteristics to become a sustainable power source, such as ultralight weight, low noise, and high durability. By introducing the air-breakdown model, the RFCB-TENG achieved an output peak voltage of 648 V, a current of 8.1 mA cm3 , and an optimum power of 162.7 mW cm3 . The structure of the RFCB-TENG is systemically optimized depending on the design parameters to realize the optimum output performance. Finally, the RFCB-TENG operated 500 LEDs and 30-W commercial lamps. This work paves the guideline for effectively fabricating the TENG using waste-materials while exhibiting outstanding characteristics.

Photocatalytic degradation of 1,4-dioxane using liquid phase plasma on visible light photocatalysts.

The compound 1,4-dioxane (DO) irritates the eyes, skin, and mucous membrane and is classified as a carcinogen. In this study, the decomposition of DO by photocatalytic reaction using liquid phase plasma (LPP) with photocatalyst was suggested. Plasma was directly discharged as an aqueous DO solution to enhance photocatalytic decomposition activity. To increase the decomposition efficiency of DO by plasma, bismuth ferrite (BFO) prepared by a sol-gel method was introduced as a visible-light photocatalyst. In the application of LPP and BFO photocatalyst, the decomposition of DO by photocatalytic reaction was evaluated. BFO showed UV-vis diffusion reflectance spectroscopy results of absorption of UV and visible light over 600 nm, with a bandgap of approximately 2.2 eV. BFO showed visible light photochemical reaction characteristics to decompose particulate matter (PM) in the irradiation of 6 W visible light LED lamps. It seems that the narrow bandgap of BFO led to the photocatalytic activity in the visible light. In the decomposition reaction of DO with a photocatalyst and LPP, BFO showed better decomposition efficiency than TiO2. BFO can cause photocatalytic reactions in both UV and visible light in the case of LPP irradiation, which emits strong ultraviolet and visible light.

Facile Preparation of Ni-Co Bimetallic Oxide/Activated Carbon Composites Using the Plasma in Liquid Process for Supercapacitor Electrode Applications.

In this study, a plasma in a liquid process (PiLP) was used to facilely precipitate bimetallic nanoparticles composed of Ni and Co elements on the surface of activated carbon. The physicochemical and electrochemical properties of the fabricated composites were evaluated to examine the potential of supercapacitors as electrode materials. Nickel and cobalt ions in the aqueous reactant solution were uniformly precipitated on the AC surface as spherical nanoparticles with a size of about 100 nm by PiLP reaction. The composition of nanoparticles was determined by the molar ratio of nickel and cobalt precursors and precipitated in the form of bimetallic oxide. The electrical conductivity and specific capacitance were increased by Ni-Co bimetallic oxide nanoparticles precipitated on the AC surface. In addition, the electrochemical performance was improved by stable cycling stability and resistance reduction and showed the best performance when the molar ratios of Ni and Co precursors were the same.

Characterization of hidden rules linking symptoms and selection of acupoint using an artificial neural network model.

Comprehension of the medical diagnoses of doctors and treatment of diseases is important to understand the underlying principle in selecting appropriate acupoints. The pattern recognition process that pertains to symptoms and diseases and informs acupuncture treatment in a clinical setting was explored. A total of 232 clinical records were collected using a Charting Language program. The relationship between symptom information and selected acupoints was trained using an artificial neural network (ANN). A total of 11 hidden nodes with the highest average precision score were selected through a tenfold cross-validation. Our ANN model could predict the selected acupoints based on symptom and disease information with an average precision score of 0.865 (precision, 0.911; recall, 0.811). This model is a useful tool for diagnostic classification or pattern recognition and for the prediction and modeling of acupuncture treatment based on clinical data obtained in a real-world setting. The relationship between symptoms and selected acupoints could be systematically characterized through knowledge discovery processes, such as pattern identification.

Heterogeneous photocatalytic degradation and hydrogen evolution from ethanolamine nuclear wastewater by a liquid phase plasma process.

Ethanolamine in a wastewater which is released from nuclear power plant was decomposed using a plasma discharged into the solution directly. Ni-TiO2 supported on mesoporous materials were employed as a photocatalyst. The photocatalytic reaction using the liquid phase plasma led to a degradation of ethanolamine with hydrogen evolution, simultaneously. The ethanolamine in the wastewater was degraded over 90% on the photocatalytic decomposition reaction by irradiation of liquid phase plasma. The rate of hydrogen evolution increased significantly with Ni incorporation on TiO2 because the bandgap was reduced with Ni incorporation on TiO2. Incorporating Ni on TiO2 nanocrystallites brought out an improvement of the ethanolamine degradation with hydrogen generation. The rate of hydrogen evolution in the ethanolamine-containing aqueous solution was increased in comparison with that in pure water. Additional hydrogen evolution by the photodecomposition of ethanolamine was attributed to the increasing H2 production.

Heterogeneous copper catalyst for the cycloaddition of azides and alkynes without additives under ambient conditions.

A new copper catalyst was developed by immobilizing copper nanoparticles in aluminum oxyhydoxide fiber. The catalyst showed high catalytic activity for the (3+2) Huisgen cycloaddition of nonactivated alkynes as well as activated ones with various azides at room temperature. The catalyst was recycled five times without significant loss of activity.

Magnetically separable Pd catalyst for highly selective epoxide hydrogenolysis under mild conditions.

A magnetically separable palladium catalyst was synthesized simply through a sol-gel process incorporating palladium nanoparticles and superparamagnetic iron oxide nanoparticles in aluminum oxyhydroxide matrix, which is highly active and selective for epoxide hydrogenolysis at room temperature under 1 atm H2. The catalyst was recycled for 25 times without loss of the activity.

Acceptor-free alcohol dehydrogenation by recyclable ruthenium catalyst.

An efficient oxidant-free oxidation for a wide range of alcohols was achieved by a recyclable ruthenium catalyst. The catalyst was prepared from readily available reagents by a one-pot synthesis through nanoparticle generation and gelation. [structure: see text]

Biaxial Dielectrophoresis Force Spectroscopy: A Stoichiometric Approach for Examining Intermolecular Weak Binding Interactions.

The direct quantification of weak intermolecular binding interactions is very important for many applications in biology and medicine. Techniques that can be used to investigate such interactions under a controlled environment, while varying different parameters such as loading rate, pulling direction, rupture event measurements, and the use of different functionalized probes, are still lacking. Herein, we demonstrate a biaxial dielectrophoresis force spectroscopy (BDFS) method that can be used to investigate weak unbinding events in a high-throughput manner under controlled environments and by varying the pulling direction (i.e., transverse and/or vertical axes) as well as the loading rate. With the BDFS system, we can quantitatively analyze binding interactions related to hydrogen bonding or ionic attractions between functionalized microbeads and a surface within a microfluidic device. Our BDFS system allowed for the characterization of the number of bonds involved in an interaction, bond affinity, kinetic rates, and energy barrier heights and widths from different regimes of the energy landscape.

Rhodium nanoparticles entrapped in boehmite nanofibers: recyclable catalyst for arene hydrogenation under mild conditions.

A new recyclable rhodium catalyst was synthesized by a simple procedure from readily available reagents, which showed high activities in the hydrogenation of various arenes under 1 atm H2 at room temperature.

Primary mesenteric carcinoid tumor.

Primary mesenteric carcinoid tumor is very rare, although secondary mesenteric involvement is common, reported as 40% to 80%. And distant metastasis rate reported as 80% to 90%, when the size is larger than 2 cm. We present a case of very rare primary mesenteric carcinoid tumor showing benign character though large size. The patient visited St. Vincent's Hospital, The Catholic University of Korea with increasing palpable abdominal mass. At laparotomy, a well encapsulated mass arising from the mesentery near the ligament of Treitz was found without any adjacent organ invasion or distant metastasis. The mass was measured as 8.2 × 7.3 cm and histopathologically benign character. At 11 months of follow up, the patient was recurrence free.

Microfluidic multifunctional probe array dielectrophoretic force spectroscopy with wide loading rates.

The simultaneous investigation of a large number of events with different types of intermolecular interactions, from nonequilibrium high-force pulling assays to quasi-equilibrium unbinding events in the same environment, can be very important for fully understanding intermolecular bond-rupture mechanisms. Here, we describe a novel dielectrophoretic force spectroscopy technique that utilizes microsized beads as multifunctional probes for parallel measurement of intermolecular forces with an extremely wide range of force rate (10(-4) to 10(4) pN/s) inside a microfluidic device. In our experiments, various forces, which broadly form the basis of all molecular interactions, were measured across a range of force loading rates by multifunctional probes of various diameters with a throughput of over 600 events per mm(2), simultaneously and in the same environment. Furthermore, the individual bond-rupture forces, the parameters for the characterization of entire energy landscapes, and the effective stiffness of the force spectroscopy were determined on the basis of the measured results. This method of determining intermolecular forces could be very useful for the precise and simultaneous examination of various molecular interactions, as it can be easily and cost-effectively implemented within a microfluidic device for a range of applications including immunoassays, molecular mechanics, chemical and biological screening, and mechanobiology.

Gastrokine 1 functions as a tumor suppressor by inhibition of epithelial-mesenchymal transition in gastric cancers.

PURPOSE: Gastrokine 1 (GKN1) plays an important role in the gastric mucosal defense mechanism and also acts as a functional gastric tumor suppressor. The specific aim of this study was to determine the molecular mechanisms underlying GKN1 tumor suppressor activity in the progression of gastric cancers. METHODS: We examined the effect of GKN1 on epithelial-mesenchymal transition (EMT) and cell migration in GKN1-transfected and recombinant GKN1-treated AGS gastric cancer cells using in vitro wound healing, microchemotaxis, and invasion assays. RESULTS: In GKN1-transfected AGS cells, we observed inhibition of cell migration and invasion in wound healing, transwell and Matrigel assay. Also, GKN1-transfected and recombinant GKN1-treated AGS cells showed decreased levels of ROS and expression of phosphatidylinositol 3-kinase (PI3K)/Akt pathway proteins, concomitant with re-expression of E-cadherin and decreased expression of cytoplasmic and nuclear expression of ß-catenin, slug, snail, fibronectin, and vimentin. CONCLUSIONS: These data suggest that the GKN1 gene may play an important role in the progression of sporadic gastric cancers via inhibition of EMT and cancer cell migration.